Proximity sensor with adaptive threshold

• US 6,933,922 B2
• Filed: 01/09/2004
• Issued: 08/23/2005
• Est. Priority Date: 01/30/2002
• Status: Expired due to Term

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Casebolt, Mark W., Lee, Mark R.
• Primary Examiner(s): Gutierrez, Diego
• Assistant Examiner(s): Reis, Travis
• Application Number:
  US10/753,343
• Publication Number:
  US 20040142705A1
• Time in Patent Office: 592 Days
• Field of Search: 250/221, 250/222.1, 250/227.22, 250/227.21, 345/157, 345/163, 345/164, 345/165, 345/166, 340/506, 340/507, 340/555, 340/556, 340/557, 340/541, 340/545.1
• US Class Current: 345/157
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode
• CPC Class Codes: G06F 1/3231 Monitoring the presence, absence or movement of users
• CPC Class Codes: G06F 1/3259 Power saving in cursor control device, e.g. mouse, joystick, trackball
• CPC Class Codes: G06F 3/03543 Mice or pucks G06F3/03541 takes precedence
• CPC Class Codes: H03K 2217/94026 Automatic threshold calibration; e.g. threshold automatically adapts to ambient conditions or follows variation of input
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A proximity sensor measures receptor output with an energy source deactivated. The sensor then measures receptor output with the energy source activated. The measurements with the energy source activated are compared to the measurements with the energy source deactivated to compensate for the effect of ambient conditions. A near condition is recognized if the change between the two groups of measurements exceeds a designated value. To compensate for receptor output that may decrease after reaching a peak value during approach of an object, a near condition can be maintained until the change between the two groups of measurements no longer exceeds a different designated value. Multiple sensors can be used to avoid false near conditions caused by, e.g., placing a device equipped with the sensors next to a stationary object. In one embodiment, a sensor comprises an infrared light emitting diode and a phototransistor.

Claims

1. A data input device, comprising:

a first proximity detector located at a first position on the device;

a second proximity detector located at a second position on the device; and

a processor in communication with the first and second proximity detectors, and configured to recognize an object-near condition only if both the first detector and the second detector detect an object in close proximity wherein the first proximity detector comprises a first electromagnetic energy source which can be selectively activated and deactivated and a first receptor which generates an output that varies over time in response to exposure to electromagnetic energy;

the second proximity detector comprises a second electromagnetic energy source which can be selectively activated and deactivated and a second receptor which generates an output that varies over time in response to exposure to electromagnetic energy; and

the processor is in communication with the first and second sources and with the first and second receptors, and configured to;

activate and deactivate the first source and the second source, sample output of the first receptor and of the second receptor, store a first indicator for receptor output samples bearing a first relation to a threshold value of receptor output, store a second indicator for receptor output samples bearing a second relation to the threshold value, compare a first set of indicators stored during an interval when the first source is deactivated with a second set of indicators stored during an interval when the first source is activated, compare a third set of indicators stored during an interval when the second source is deactivated with a fourth set of indicators stored during an interval when the second source is activated, and recognize an object-near condition if the comparisons identify a triggering level of difference between the first and second sets and between the third and fourth sets.

2. The device of claim 1 wherein the first position is at a first surface of the device and the second position is at a second surface of the device.

3. The device of claim 2, wherein the device is a hand-held computer pointing device.

4. The computer pointing device of claim 3 wherein the first surface is a side surface of the computer pointing device and the second surface is a top surface of the computer pointing device.

5. The device of claim 1, wherein the processor is configured to continue recognizing an object-near condition until the comparison identifies a second level of difference between the third and fourth sets that is lesser in magnitude than the triggering level.

6. The data input device of claim 1, wherein the processor is further configured to compensate for ambient conditions when operating the first or second proximity detector.

7. The data input device of claim 1, wherein the processor is further configured to check for anomalous input from at least one of the first or second proximity detectors.

8. The data input device of claim 1, wherein the processor is further configured to perform two checks for anomalous input upon a single input from at least one of the first or second proximity detectors.

9. The data input device of claim 1, wherein the processor is further configured to:

(a) receive input from one of the first and second proximity detectors indicative of an object in close proximity and receive input from the other of the first and second proximity detectors indicative of no object in close proximity,

(b) determine, based on the inputs of step (a), the absence of an object-near condition,

(c) subsequently receive input from one of the first and second proximity detectors indicative of an object in close proximity and receive input from the other of the first and second proximity detectors indicative of an object in close proximity, and

(d) determine, based on the inputs of step (c), the existence of an object-near condition.

10. The data input device of claim 1, wherein at least one of the first and second proximity detectors comprises a light detecting element.

11. The data input device of claim 1, wherein the first proximity detector comprises a first light detecting element and the second proximity detector comprises a second light detecting element.

12. The data input device of claim 11, wherein the data input device is a computer mouse, the first position is a side of the computer mouse and the second position is a top of the computer mouse.

13. The data input device of claim 1, wherein the processor is configured to:

recognize an object-near condition only if both the first proximity detector and the second proximity detector detect an object in close proximity, and

not recognize an object near condition if only one of the first and the second proximity detectors detects an object in close proximity.

14. The data input device of claim 1, wherein the second proximity detector is capable of detecting an object in close proximity independent of detection by the first proximity detector.

15. The data input device of claim 1, wherein the processor is in communication with and receiving separate signals from the first and second proximity detectors.